As an alternative strategy with Mechanical Pandaren Hatchling, you can run it with 1, 1, 2 as follows:

Turn 1: Decoy
Turns 2-4: Breath until Pixiebell is dead.
Turns 5-6: Rotate in the leveling pets.
Turn 7: Bombing Run.
From here, just use Breath on Tally. The Mechanical Pandaren Hatchling will more often than not die, but when it does, it will auto-rez and the Bombing Run will complete, taking out Tally. From here, just use Breath on Doodle until it dies.

Start with Turret Metal Fist Metal Fist
Rinse and repeat till Pixiebell is dead. Then Doddles comes in
Repair At this time Tally will come in
Start with Turret Metal Fist Metal Fist
Rinse and repeat till Tally is dead. Doodles will come back in.
Change to carrie pet(s) (no need to attack) and back to Clockwork Gnome and finish off
Doddles.